title: Inactivation of HDAC5 by SIK1 in AICAR-treated C2C12 myoblasts.
abstract: Salt inducible kinase (SIK) 1, a member of the AMP-activated kinase (AMPK) family, is activated by the AMPK-activator LKB1 which phosphorylates SIK1 at Thr182. The activated SIK1 then auto-phosphorylates its Ser186 located at the +4 position of Thr182. The phospho-Ser186 is essential for sustained activity of SIK1, which is maintained by sequential phosphorylation at Ser186-Thr182 by glycogen synthase kinase (GSK)-3beta. Meanwhile, SIK1 represses the transcription factor cAMP-response element binding protein (CREB) by phosphorylating its co-activator transducer of regulated CREB activity (TORC). Recently, histone deacetylase (HDAC) 5 was identified as a new substrate of SIK1. Inhibition of SIK1 or AMPK results in the stimulation of glyconeogensis in the liver by enhancing dephosphorylation of TORC2 followed by up-regulation of peroxisome proliferator-activated receptor coactivator (PGC)-1alpha gene expression. However, expression of the PGC-1alpha gene has been found to be repressed in LKB1-defective muscle cells. Our findings show that the AMPK agonist 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR)-dependent expression of PGC-1alpha is diminished by inhibitors of GSK-3beta or SIKs in C2C12 myoblasts. Treatment with AICAR or the overexpression of SIK1 induces nuclear export of HDAC5 followed by the activation of myogenic transcription factor (MEF)-2C. The levels of phosphorylation at Thr182 and Ser186 of SIK1 in AICAR-treated C2C12 cells are elevated, and GSK-3beta enzyme purified from AICAR-treated cells shows enhanced phosphorylation activity of SIK1 in vitro. These observations suggest that GSK-3 beta and SIK1 may play important roles in the regulation of PGC-1alpha gene expression by inactivating HDAC5 followed by activation of MEF2C.
authors.affiliation: Laboratory of Cell Signaling and Metabolism, National Institute of Biomedical Innovation, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takemori
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Katoh Hashimoto
authors.forename: Jun
authors.initials: J
authors.lastname: Nakae
authors.forename: Eric N
authors.initials: EN
authors.lastname: Olson
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Okamoto
mesh_terms: D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism / Q000502:physiology; D000071679:Glycogen Synthase Kinase 3 beta; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D032446:Myoblasts / Q000187:drug effects* / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000378:metabolism / Q000502:physiology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D051381:Rats; D012265:Ribonucleotides / Q000494:pharmacology*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013912:Threonine / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors
chemical_list: D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; D018006:Myogenic Regulatory Factors; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012265:Ribonucleotides; D015534:Trans-Activators; D014157:Transcription Factors; D013912:Threonine; D000620:Aminoimidazole Carboxamide; D012694:Serine; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; D017346:Protein Serine-Threonine Kinases; C120299:Sik1 protein, rat; D038362:Glycogen Synthase Kinase 3; C498618:Hdac5 protein, mouse; D006655:Histone Deacetylases; C031143:AICA ribonucleotide